I test myself with at least two monitors of different brands at the same sitting. It's amazing how one can be significantly higher. One can find me as Stage 2 while the other as normal. My case is a little confusing because my systolic is high while diastolic is normal. I’m on a lifetime anti-hypertension regimen. One of the monitors actually takes three readings at one sitting and calculates the average of the three readings. It's sobering to see the large variation in the readings even though they are only a minute apart. All the major retailers in the US stock Omron, which is a Japanese brand. Sometimes it's the only brand they carry. Medline may not be familiar because it's a supplier to hospitals and medical professionals that is now offering retail sales. My readings are surprisingly much lower in Thailand, despite gaining weight. When I return home, they immediately start creeping up. An upper-arm cuff on the left arm is probably better simply because it's closer to the heart. There are now wrist monitors. Most smart watches from China take blood pressure readings automatically. They don't have pressure sensors, so the values are calculated based on blood flow. The faster the flow, the higher the pressure. Since the readings are calculated, the watches need to be calibrated. The watches can track your blood pressure throughout the day. They can be set to sound an alarm if your blood pressure spikes. After I swim laps, the next day my heart rate and blood pressure will be lower. There are now smart watches from China with a real cuff between the wrist and the band. A mini air pump inside the watch inflates the cuff.